Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/949,547 filed on Jul. 13, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches.

An embodiment of the transmission includes an input member, an outputmember, first, second, third and fourth planetary gear sets each havingfirst, second and third members, a first interconnecting membercontinuously interconnecting the third member of the first planetarygear set with a stationary element, a second interconnecting membercontinuously interconnecting the first member of the second planetarygear set with the stationary element, a third interconnecting membercontinuously interconnecting the third member of the second planetarygear set with the second member of the third planetary gear set, afourth interconnecting member continuously interconnecting the secondmember of the third planetary gear set with the second member of thefourth planetary gear set, and a fifth interconnecting membercontinuously interconnecting the third member of the third planetarygear set with the first member of the fourth planetary gear set. Fivetorque transmitting mechanisms are selectively engageable tointerconnect one of the first members, second members, and third memberswith at least one of the first members, second members, and thirdmembers. The torque transmitting mechanisms are selectively engageablein combinations of at least two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

In one aspect of the present invention, a first of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the first member of the first planetary gear set and theoutput member with the third member of the fourth planetary gear set.

In another aspect of the present invention, a second of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the second planetary gear set with at least one of theinput member, the third member of the third planetary gear set, and thefirst member of the fourth planetary gear set.

In yet another aspect of the present invention, a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second member of the second planetary gear set with the first memberof the third planetary gear set.

In yet another aspect of the present invention, a fourth of the fivetorque transmitting mechanisms is selectively engageable to interconnectat least one of the first member of the first planetary gear set and theoutput member with the first member of the third planetary gear set.

In yet another aspect of the present invention, a fifth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second member of the first planetary gear set with at least one ofthe second member of the fourth planetary gear set, the second member ofthe third planetary gear set, and the third member of the secondplanetary gear set.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the input member iscontinuously interconnected with at least one of the third member of thethird planetary gear set and the first member of the fourth planetarygear set and wherein the output member is continuously interconnectedwith the first member of the first planetary gear set.

In yet another aspect of the present invention, the torque transmittingmechanisms are clutches.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having first a sun gear, a carrier member, anda ring gear, wherein the input member is continuously interconnectedwith at least one of the ring gear of the third planetary gear set andthe sun gear of the fourth planetary gear set and wherein the outputmember is continuously interconnected with the sun gear of the firstplanetary gear set, a first interconnecting member continuouslyinterconnecting the ring gear of the first planetary gear set with astationary element, a second interconnecting member continuouslyinterconnecting the sun gear of the second planetary gear set with thestationary element, a third interconnecting member continuouslyinterconnecting the ring gear of the second planetary gear set with thecarrier member of the third planetary gear set, a fourth interconnectingmember continuously interconnecting the carrier member of the thirdplanetary gear set with the carrier member of the fourth planetary gearset, and a fifth interconnecting member continuously interconnecting thering gear of the third planetary gear set with the sun gear of thefourth planetary gear set. A first torque transmitting mechanism isselectively engageable to interconnect at least one of the sun gear ofthe first planetary gear set and the output member with the ring gear ofthe fourth planetary gear set, a second torque transmitting mechanism isselectively engageable to interconnect the carrier member of the secondplanetary gear set with at least one of the input member, the ring gearof the third planetary gear set, and the sun gear of the fourthplanetary gear set, a third torque transmitting mechanism is selectivelyengageable to interconnect the carrier member of the second planetarygear set with the sun gear of the third planetary gear set, a fourthtorque transmitting mechanism is selectively engageable to interconnectat least one of the sun gear of the first planetary gear set and theoutput member with the sun gear of the third planetary gear set, and afifth torque transmitting mechanism is selectively engageable tointerconnect the carrier member of the first planetary gear set with atleast one of the carrier member of the fourth planetary gear set, thecarrier member of the third planetary gear set, and the ring gear of thesecond planetary gear set. The torque transmitting mechanisms areselectively engageable in combinations of at least two to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the eight speed automatic transmission of the presentinvention has an arrangement of permanent mechanical connections betweenthe elements of the four planetary gear sets. A first component orelement of a first planetary gear set is permanently coupled to astationary element. A first component or element of a second planetarygear set is permanently coupled to a stationary element. A secondcomponent or element of the second planetary gear set is permanentlycoupled to a second component or element of a third planetary gear setand to a second component or element of a fourth planetary gear set.Finally, a first component or element of the third planetary gear set ispermanently coupled to a first component or element of the fourthplanetary gear set.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. Further explanation ofthe format, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input member 12 is coupled to the third node 20C of the fourthplanetary gear set 20. The output member 22 is coupled to the third node14C of the first planetary gear set 14. The second node 20B of thefourth planetary gear set 20 is coupled to the first node 18A of thethird planetary gear set 18 and to the second node 16B of the secondplanetary gear set 16. The third node 20C of the fourth planetary gearset 20 is coupled to the second node 18B of the third planetary gear set18. The first node 16A of the second planetary gear set 16 is coupled toa ground, stationary element, or a transmission housing 40. The firstnode 14A of the first planetary gear set 14 is coupled to a ground, astationary element, or the transmission housing 40.

A first clutch 26 selectively connects the first node 20A of the fourthplanetary gear set 20 with the third node 14C of the first planetarygear set 14. A second clutch 28 selectively connects the second node 18Bof the third planetary gear set 18 with the third node 16C of the secondplanetary gear set 16. A third clutch 30 selectively connects the thirdnode 18C of the third planetary gear set 18 with the third node 16C ofthe second planetary gear set 16. A fourth clutch 32 selectivelyconnects the third node 18C of the third planetary gear set 18 with thethird node 14C of the first planetary gear set 14. A fifth clutch 34selectively connects the second node 16B of the second planetary gearset 16 with the second node 14B of the first planetary gear set 14.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the eight speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aplanet gear carrier member 14B and a ring gear member 14A. The sun gearmember 14C is connected for common rotation with the output member 22.The ring gear member 14A is connected to a first shaft orinterconnecting member 42 that is connected to a stationary element orthe transmission housing 40 in order to restrict the ring gear member14A from rotating relative to a stationary element or the transmissionhousing 40. The planet gear carrier member 14B rotatably supports a setof planet gears 14D (only one of which is shown) and is connected forcommon rotation with a second shaft or interconnecting member 44. Theplanet gears 14D are each configured to intermesh with both the sun gearmember 14C and the ring gear member 14A.

The planetary gear set 16 includes a sun gear member 16A, a ring gearmember 16B, and a planet carrier member 16C that rotatably supports aset of first planet gears 16D intermeshed with a set of second planetgears 16E. The sun gear member 16A is connected for common rotation witha third shaft or interconnecting member 46 that is connected to astationary element or the transmission housing 40 in order to restrictthe sun gear member 16A from rotating relative to the stationary elementor the transmission housing 40. The planet carrier member 16C isconnected for common rotation with a fourth shaft or interconnectingmember 48 and with a fifth shaft or interconnecting member 50. The ringgear member 16B is connected for common rotation with a sixth shaft orinterconnecting member 52. The first planet gears 16D are configured tointermesh with the ring gear member 16B and the second planet gears 16Eare configured to intermesh with the sun gear member 16A.

The planetary gear set 18 is a planetary gear set that includes a sungear member 18C, a ring gear member 18B and a planet carrier member 18Athat rotatably supports a set of first planet gears 18D intermeshed witha set of second planet gears 18E. The sun gear member 18C is connectedfor common rotation with a seventh shaft or interconnecting member 54and with an eighth shaft or interconnecting member 56. The ring gearmember 18B is connected for common rotation with the input member 12.The planet carrier member 18A is connected for common rotation with thesixth interconnecting member 52 and with a ninth shaft orinterconnecting member 58. The first planet gears 18D are configured tointermesh with the ring gear member 18B and the second planet gears 18Eare configured to intermesh with the sun gear member 18C.

The planetary gear set 20 is a planetary gear set that includes a sungear member 20C, a ring gear member 20A and a planet carrier member 20Bthat rotatably supports a set of planet gears 20D. The sun gear member20C is connected for common rotation with the input member 12. The ringgear member 20A is connected for common rotation with a tenth shaft orinterconnecting member 60. The planet carrier member 20B is connectedfor common rotation with the ninth interconnecting member 58 and with aneleventh shaft or interconnecting member 62. The planet gears 20D areeach configured to intermesh with both the sun gear member 20C and thering gear member 20A.

The input shaft or member 12 is preferably continuously connected to anengine (not shown) or to a turbine of a torque converter (not shown).The output shaft or member 22 is preferably continuously connected withthe final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches 26, 28, 30, 32, 34 allowfor selective interconnection of the shafts or interconnecting members,members of the planetary gear sets and the housing. For example, thefirst clutch 26 is selectively engageable to connect the tenthinterconnecting member 60 with the output member 22. The second clutch28 is selectively engageable to connect the fourth interconnectingmember 48 with the input member 12. The third clutch 30 is selectivelyengageable to connect the fifth interconnecting member 50 with theseventh interconnecting member 54. The fourth clutch 32 is selectivelyengageable to connect the eighth interconnecting member 56 with theoutput member 22. The fifth clutch 34 is selectively engageable toconnect the second interconnecting member 44 with the eleventhinterconnecting member 62.

Referring now to FIGS. 2 and 3, the operation of the embodiment of theeight speed transmission 10 will be described. It will be appreciatedthat the transmission 10 is capable of transmitting torque from theinput shaft or member 12 to the output shaft or member 22 in at leasteight forward speed or torque ratios and at least one reverse speed ortorque ratio. Each forward and reverse speed or torque ratio is attainedby engagement of one or more of the torque-transmitting mechanisms (i.e.first clutch 26, second clutch 28, third clutch 30, fourth clutch 32,and fifth clutch 34), as will be explained below. FIG. 3 is a truthtable presenting the various combinations of torque-transmittingmechanisms that are activated or engaged to achieve the various gearstates. Actual numerical gear ratios of the various gear states are alsopresented although it should be appreciated that these numerical valuesare exemplary only and that they may be adjusted over significant rangesto accommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, the first clutch 26 and the fifth clutch 34are engaged or activated. The first clutch 26 connects the tenthinterconnecting member 60 with the output member 22. The fifth clutch 34connects the second interconnecting member 44 with the eleventhinterconnecting member 62. Likewise, the eight forward ratios areachieved through different combinations of clutch engagement, as shownin FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches not specifically referenced in a given gear stateare inactive or disengaged and, second of all, that during gear shifts,i.e., changes of gear state, between at least adjacent gear states, aclutch engaged or activated in both gear states will remain engaged oractivated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the third member of the first planetary gear set with astationary element; a second interconnecting member continuouslyinterconnecting the first member of the second planetary gear set withthe stationary element; a third interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe second member of the third planetary gear set; a fourthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the second member of the fourthplanetary gear set; a fifth interconnecting member continuouslyinterconnecting the third member of the third planetary gear set withthe first member of the fourth planetary gear set; and five torquetransmitting mechanisms selectively engageable to interconnect one ofthe first members, second members, and third members with at least oneof the first members, second members, and third members, and wherein thetorque transmitting mechanisms are selectively engageable incombinations of at least two to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 2. The transmission of claim 1 wherein a first of thefive torque transmitting mechanisms is selectively engageable tointerconnect at least one of the first member of the first planetarygear set and the output member with the third member of the fourthplanetary gear set.
 3. The transmission of claim 2 wherein a second ofthe five torque transmitting mechanisms is selectively engageable tointerconnect the second member of the second planetary gear set with atleast one of the input member, the third member of the third planetarygear set, and the first member of the fourth planetary gear set.
 4. Thetransmission of claim 3 wherein a third of the five torque transmittingmechanisms is selectively engageable to interconnect the second memberof the second planetary gear set with the first member of the thirdplanetary gear set.
 5. The transmission of claim 4 wherein a fourth ofthe five torque transmitting mechanisms is selectively engageable tointerconnect at least one of the first member of the first planetarygear set and the output member with the first member of the thirdplanetary gear set.
 6. The transmission of claim 5 wherein a fifth ofthe five torque transmitting mechanisms is selectively engageable tointerconnect the second member of the first planetary gear set with atleast one of the second member of the fourth planetary gear set, thesecond member of the third planetary gear set, and the third member ofthe second planetary gear set.
 7. The transmission of claim 1 whereinthe first members are sun gears, the second members are carrier members,and the third members are ring gears.
 8. The transmission of claim 1wherein the input member is continuously interconnected with at leastone of the third member of the third planetary gear set and the firstmember of the fourth planetary gear set and wherein the output member iscontinuously interconnected with the first member of the first planetarygear set.
 9. The transmission of claim 1 wherein the torque transmittingmechanisms are clutches.
 10. The transmission of claim 1 wherein thestationary element is a transmission housing.
 11. A transmissioncomprising: an input member; an output member; first, second, third andfourth planetary gear sets each having first, second and third members,wherein the input member is continuously interconnected with at leastone of the third member of the third planetary gear set and the firstmember of the fourth planetary gear set and wherein the output member iscontinuously interconnected with the first member of the first planetarygear set; a first interconnecting member continuously interconnectingthe third member of the first planetary gear set with a stationaryelement; a second interconnecting member continuously interconnectingthe first member of the second planetary gear set with the stationaryelement; a third interconnecting member continuously interconnecting thethird member of the second planetary gear set with the second member ofthe third planetary gear set; a fourth interconnecting membercontinuously interconnecting the second member of the third planetarygear set with the second member of the fourth planetary gear set; afifth interconnecting member continuously interconnecting the thirdmember of the third planetary gear set with the first member of thefourth planetary gear set; a first torque transmitting mechanismselectively engageable to interconnect at least one of the first memberof the first planetary gear set and the output member with the thirdmember of the fourth planetary gear set; a second torque transmittingmechanism selectively engageable to interconnect the second member ofthe second planetary gear set with at least one of the input member, thethird member of the third planetary gear set, and the first member ofthe fourth planetary gear set; a third torque transmitting mechanismselectively engageable to interconnect the second member of the secondplanetary gear set with the first member of the third planetary gearset; a fourth torque transmitting mechanism selectively engageable tointerconnect at least one of the first member of the first planetarygear set and the output member with the first member of the thirdplanetary gear set; and a fifth torque transmitting mechanismselectively engageable to interconnect the second member of the firstplanetary gear set with at least one of the second member of the fourthplanetary gear set, the second member of the third planetary gear set,and the third member of the second planetary gear set, and wherein thetorque transmitting mechanisms are selectively engageable incombinations of at least two to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 12. The transmission of claim 11 wherein the firstmembers are sun gears, the second members are carrier members, and thethird members are ring gears.
 13. The transmission of claim 12 whereinthe stationary element is a transmission housing.
 14. A transmissioncomprising: an input member; an output member; first, second, third andfourth planetary gear sets each having first a sun gear, a carriermember, and a ring gear, wherein the input member is continuouslyinterconnected with at least one of the ring gear of the third planetarygear set and the sun gear of the fourth planetary gear set and whereinthe output member is continuously interconnected with the sun gear ofthe first planetary gear set; a first interconnecting membercontinuously interconnecting the ring gear of the first planetary gearset with a stationary element; a second interconnecting membercontinuously interconnecting the sun gear of the second planetary gearset with the stationary element; a third interconnecting membercontinuously interconnecting the ring gear of the second planetary gearset with the carrier member of the third planetary gear set; a fourthinterconnecting member continuously interconnecting the carrier memberof the third planetary gear set with the carrier member of the fourthplanetary gear set; a fifth interconnecting member continuouslyinterconnecting the ring gear of the third planetary gear set with thesun gear of the fourth planetary gear set; a first torque transmittingmechanism selectively engageable to interconnect at least one of the sungear of the first planetary gear set and the output member with the ringgear of the fourth planetary gear set; a second torque transmittingmechanism selectively engageable to interconnect the carrier member ofthe second planetary gear set with at least one of the input member, thering gear of the third planetary gear set, and the sun gear of thefourth planetary gear set; a third torque transmitting mechanismselectively engageable to interconnect the carrier member of the secondplanetary gear set with the sun gear of the third planetary gear set; afourth torque transmitting mechanism selectively engageable tointerconnect at least one of the sun gear of the first planetary gearset and the output member with the sun gear of the third planetary gearset; and a fifth torque transmitting mechanism selectively engageable tointerconnect the carrier member of the first planetary gear set with atleast one of the carrier member of the fourth planetary gear set, thecarrier member of the third planetary gear set, and the ring gear of thesecond planetary gear set, and wherein the torque transmittingmechanisms are selectively engageable in combinations of at least two toestablish at least eight forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 15. Thetransmission of claim 14 wherein the stationary element is atransmission housing.